We have searched for the decay phi -> K0-K0bar-gamma by detecting KS pairs plus a photon and with the KS-mesons decaying to pi+ pi-, in a sample of about 1.5 x 10^9 phi-decays collected by the KLOE experiment at DAFNE. The reaction proceeds through the intermediate states f0(980)-gamma, a0(980)-gamma. We find five events with 3.2 events expected from background processes. We obtain the upperlimit: BR(phi -> K0-Kobar-gamma < 1.9 x 10^(-8) at 90% CL.